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GLM 5.3 by Z.ai Coding agent

Chat with GLM 5.3 for free

GLM 5.3 is Z.ai's open-weight coding and agentic model, with always-on reasoning and a 1M-token context window for large codebases. Start typing, no sign-up needed.

Free in ChatdaySwitch models any timeCompare with other models
Live preview

See how GLM 5.3 thinks

Pick a task and watch a sample answer stream in. Open the same prompt in Chatday when you’re ready.

Why does this return undefined? const u = users.find(u => u.id = id)

The bug is in the arrow body: u.id = id assigns instead of compares, so the callback returns the assigned value and .find never matches the way you expect.

Fix it with a strict comparison:

const u = users.find(u => u.id === id);

Use === to compare. A single = is assignment, which is why you saw undefined.

Illustrative preview: your real answers run in Chatday. Continue in Chatday
Strengths

What makes GLM 5.3 stand out

Strong coding and tool use
Sustains long-running agentic tasks
1M-token context window
Open weights
At a glance

GLM 5.3 specifications

1M
Context window
1M
Max output
Text · Code
Modality
Frontier
Speed
Free & Pro
Available in Chatday
ProviderZ.ai
Model familyGLM 5 series
Context window1,000,000 tokens
Max output1,000,000 tokens
ModalityText · Code
Input price$1.4 / 1M tokens
Output price$4.4 / 1M tokens
Tool / function callingYes
VisionNo
StreamingYes
Available in ChatdayFree & Pro

Pricing shown for reference; usage is included in your Chatday plan.

Side by side

GLM 5.3 vs other top models

Compare
Model Context Best at Input price In Chatday
GLM 5.3 1M Coding agent $1.4/M Free
Grok 4.6 500K Agentic reasoning $2/M Free
Claude Opus 5 1M Frontier agents $5/M Free
GPT-5.6 1.1M Flagship reasoning $2/M Free
FAQ

GLM 5.3 questions

Yes. GLM 5.3 is available on the free plan with daily limits. Pro raises the limits and adds priority access during peak times.
1M tokens: enough for very long documents, large codebases or extended conversations without losing earlier context.
Reach for GLM 5.3 on the tasks it’s built for, then switch models mid-chat in Chatday when another one fits better, no need to leave the conversation.
GLM 5.3’s weights are publicly available, so it can be self-hosted, and you can also use it instantly, with no setup, inside Chatday.

Chat with GLM 5.3 and switch models any time.

One subscription, every leading model. Start free in the Chatday web app.